1. Field of the Invention
The invention relates generally to electrostatic atomizers and more particularly to an electrostatic atomizer that generates mist of charged fine particles in the order of nanometer in size.
2. Description of the Related Art
Such sort of electrostatic atomizer is seen in, for example, the patent document of Japanese Patent Number 3260150 (European Patent Publication Number 0 486 198 A1 or U.S. Pat. No. 5,337,963). A prior art device described in the document comprises a cartridge for storage of liquid suitable for electrostatic spraying, and a high voltage means for applying electrostatic potential to the liquid. The cartridge includes a capillary structure that extends into the interior of the cartridge so as to feed liquid by capillary action from the cartridge to a spraying outlet at a tip of the capillary structure. The cartridge also includes a means for providing an electrically conductive path to allow the application of an electrostatic charge to the liquid. When the high voltage means applies the potential to the liquid at the mouth of the spraying outlet, a potential gradient is developed between innermost and outermost peripheral surfaces of the mouth, and draws the liquid across an end face of the spraying outlet towards the outermost peripheral surface. Thereby, the liquid is projected electrostatically as an array of ligaments which form a halo around the mouth.
However, the prior art device requires that water is supplied into the cartridge. Also, an electrostatic atomizer that can solve this issue has been separately made by the applicant (see Japanese Patent Application Publication Number 2006-122819). This atomizer comprises a discharge electrode, a counter electrode located opposite the discharge electrode, a cooling source that cools the discharge electrode to form thereon dew as water, and a high voltage power supply that applies high voltage for discharge across the electrodes. Thus, by cooling the discharge electrode to form dew, the trouble of supplying water can be saved.
Incidentally, the atomizer repeats the Rayleigh splitting to realize electrostatic atomization. That is, when high voltage is applied across the electrodes, a negative electronic charge concentrates on the discharge electrode, and also water held on the tip of the discharge electrode rises like a cone to form a Taylor cone. When the negative electronic charge concentrates on the tip of the Taylor cone to become high density, repulsion of the electronic charge in the high density brings about Rayleigh splitting to split and scatter the Taylor cone shaped water. Thus, in the atomizer that repeats the Rayleigh splitting to realize electrostatic atomization, stable generation of high voltage is important.